Serial I/O under 21.11

Operating Systems VxWorks
1

I am building a VxWorks 21.11 BSP for a Power Architecture board which has this kernel config item: UART support for ns16550-compatible FDT devices

I believe the entries in my .dts file are correct, as I have serial ports functional, but when I enter the command devs in the Target Shell, I get this:
→ devs
drv refs name
10 [ 3] /diffDio
9 [ 3] /dio
8 [ 3] /host.host
0 [ 3] /null
1 [ 5] /ttyS0
1 [ 3] /ttyS1
1 [ 3] /ttyS2
1 [ 3] /ttyS3
1 [ 3] /ttyS4
value = -140737488096368 = 0xffff80000003f390
→

I would expect to see entries under the /ttySN devices like this:
2 [ 3] /tyCo/0 ==> /ttyS0
2 [ 3] /tyCo/1 ==> /ttyS1
2 [ 3] /tyCo/2 ==> /ttyS2
2 [ 3] /tyCo/3 ==> /ttyS3
2 [ 3] /tyCo/4 ==> /ttyS4

Has the handling of serial I/O ports changed in 21.11?

Thank you